Centerless grinding of longitudinally contoured articles



Oct. 17, 1950 2,526,332

R. i-l'. CR AMER CENTERLESS GRINDING 0F. LONGITUDINALLY CONTOURED, ARTICLES Filed July 17, 1947 2 Sheets-Sheet 1 Ill ' INVENTOL.

HIS ATTORNEY i atented Oct. 17,

CENTERLESS GRINDING OF LONGITU- DINALLY CONTOURED ARTICLES Raymond H. Cramer, Bloomfield, N. .L, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application July 17, 1947, Serial No. 761,694

23 Claims.

across a concave grinding wheel while .supported by a work rest and a regulating wheel which oscillate as a unit around an axis, a feeding mechanism inserting .a roller onto the rest from one side of the .grinding wheel .at the beginning of a stroke and an ejector removing the roller at the end of the stroke, the return stroke being idle. It has been proposed to grind rollers in both directions of oscillation but such proposals have required two feeding mechanisms and two ejecting mechanisms. Another object of the invention is to provide a machine of this general character which will grind rollers in both directions of oscillation. with the employment of a single feeding and ejecting mechanism capable .of fast and "reliable operation. In general this object is accomplished by mountin a combined feeding and ejecting mechanism on the oscillating unit itself for actuation thereby, guiding a column of rollers downwardly between the wheels onto the work rest, and making the regulating wheel narrower than the length of the rollers 50 that ejecting fingers alongside the regulating wheel will eject a finished roller and cause the quick application of a new roller to grinding position at the end of every stroke of oscillation.

To these ends and also to improve generally upon apparatus of this character, the invention consists in the various matters hereinafter -de-.

scribed and claimed. In its broader aspects, the invention is not necessarily limited to the specific construction selected for illustrative purposes in the accompanying drawings in which Fig. 1 is a front elevation of the oscillatin unit as seen from grinding wheel side of the work rest.

Fig. 2 is a side elevation of 'Fig. 1, the position of the two wheels being additionally indicated.

Fig. 3 is a planview. of Fig. 2, the extent of oscillation of the oscillating unit being indicat ed by two broken line showings of the grinding wheel.

Fig. 4 is an exploded perspective view of four parts of the feed mechanism near the top of the oscillating unit. I

Fig. 5 is an enlarged vertical section through Iii! stroke of oscillation.

the grinding wheel and the work chute with other elements in side elevation.

Fig. 6 is a horizontal section of Fig. 5 just above the work being ground.

Fig. 7 is a perspective view of certain feeding and ejecting elements.

Fig, 8 is an exploded perspective view, parts being in section, of a work chute and associated parts.

Fig. 9 is a horizontal sectional view of a supporting post, the section being taken just above the top of the work rest. I

Fig. 10 i an exploded perspective view of a portion of the supporting post and certain clamping members for the work guides and the work rest.

. Fig. 11 is a perspective view of the supporting post.

Fig. 12 is an exploded perspective view of a reciprocating cam and its guide.

I Fig. '13 is a plan view of a work rest and guide plates.

Fig. 14 is a front view of Fig. 13.

The work piece W to be ground," herein shown as a barrelshaped roller, is supported on a blade or work rest S and a narrow regulating wheel R which oscillate as a unit to traverse the work endwise along the concave periphery of awide grinding wheel G. A feeding and ejecting mechanism is also mounted on the oscillating unit and a finished roller is ejected and a new roller is lowered onto the work rest at the end of each The rollers are urged endwise by a suitable feeder through a flexible feed tube 2. whose lower end is supported in a bushing fastened by a. set 1 into a longitudinalguideway I8 atthe top of.

the roller guide. The bottom of the roller guide has an exit opening which conducts each roller downwardly into a work chute 22 after the roller has been pushed sidewise along the guide over the opening "by an in-feed finger 24 on a rockable transfer arm 26.

.Fastened by screws in adjusted position in the bottom of the guideway I8 is a rectangular back stop 30 having slots for the screws. The back stop has a front stop face which terminates at the rear of the bottom opening in the roller guide. The back stop has a tapped openin for a vertical screw 34 which extends upwardly through a slot in a cover plate 36, a coil spring 38 being interposed between the cover plate and a nut at the top of the screw. The cover plate presses downwardly on the rollers and prevents their upward movement as they are pushed along the channel of the roller guide to the stop surface.

The chute 22 (Fig. 8) has two drilled openings 42 for screws which fasten the chute in a nearly vertical position on a web which connects the two upright legs of the bracket 6. The chute body is of U-shaped cross section with parallel end walls 43 and a bottom or side wall 44 which extends downwardly from the roller guide into a close proximity to the regulating wheel, the lower end of the side wall having an arcuate surface which extends into a sharp projection 46v which just clears the regulating wheel. The center line of the work chute is in the central plane of the regulating wheel. The chute has tapped openings 48 for screws which pass through drilled openings 50 of an upper cover plate 52, the cover plate having central elongated slots 54 to render the rollers visible. Two other screws similarly secure a lower cover plate 56 to the chute body, the lower cover plate having a slot 58 and a sharply pointed extension 60 which is also slit and extends into very close proximity to the grinding wheel. The upper and lower cover plates constitute a front side wall opposite to the rear side wall '54, and the lower cover plate extends downwardly farther than the side wall 44 and close to the work rest to co-operate with the regulating wheel in guiding a column of rollers onto the work rest S.

As the rollers leave the end walls 43 and approach the work rest, their ends are guided between, the adjacent parallel edges of an upper pair of arcuate clamping plates 56 which are fastened by screws in the upper portions of arcuate recesses 58 I in an upright supporting post I0. Each clamping plate has a bevelled lower surface which overlaps a similar bevel on a Work locating and guiding plate "I2 to hold the latter against the post. A similar lower pair of arcuate clamping plates 14 have their upper surfaces bevelled to overlap and clamp sr'rnilar bevels at the lower edge of the plates F2. The plates I2 have a por-- tion of their adjacent edges E6 arranged to converge downwardly to guide and center the rollers as they enter between parallel locating surfaces '53 which locate each roller endwise while supported on the work rest.

The work rest which has parallel vertical edges and bevelle'd sides 82 is fastened by a clamp 84 in a vertical recess 86 at the front of the post,

one side of the recess being undercut. The top of the work rest is very slightly longer than the rollers which are first end ground to very close tolerances. Then, when the lower portions of the parallel locating surfaces I8 are brought up against the vertical edges 80 of the work rest and clamped there, each roller is free to rotate but can have no appreciable endwise movement in either direction. The top of the work rest slants downwardly towards the regulating wheel but longitudinally it is curved to conform to the roller. The post has a base flange 88 fastened by screws to the top of an oscillating head 90. The top of the post has horizontal rabbeted rails 92 on which are fastened similar rails at the bottom of the bracket 6. The middle potrion of the post has a deep central recess 93 above which the post is divided so that the regulating wheel can approach closely to the work rest. The regulating wheel may conveniently be supported on the oscillating unit and driven by mechanism similar to that disclosed in Figs. 1 and 2 of my above cited Patent 2,156,562.

The transfer arm 26 is in the form of a yoke whose opposite arms straddle the chute 22. The lower ends of the opposite arms are connected (Fig. '7) by a web 04 behind the chute and the ends project downwardly beyond the web to form bearing hubs 96 which are split and clamped by screws to a rock shaft 98. The rock shaft is journalled in bushings in bearing bosses I00 on the spaced legs of the bracket 6. An anchor screw threaded in the web 94 is connected by a tension spring I02 to an adjusting screw I04 having a threaded adjusting knob I06 bearing on a rounded aligning washer I08 which engages a cross plate IIO fastened on the bracket 6. The split hub portion N2 of an ejector arm H4 is clamped on the rock shaft between the bearing hubs 96. The ejector arm has riveted thereto a pair of parallel, spring steel extensions H6 which straddle the narrow regulating wheel and terminate in bent tips or ejecting fingers l I8 which can be projected between the work rest and the cover plate extension 60 to eject a finished roller at one side of the grinding wheel when the oscillating unit is at either end of its stroke. The regulating wheel is narrower than the length of the work pieces so that the ejecting fingers can also pass between the guiding plates I2 as they engage the work piece near the ends.

The rock shaft 98 is cam actuated under control of the oscillating stroke. A cam engaging arm or follower I20 has a split hub clamped to one end of the rock shaft and extending upwardly. The arm has a pointed tip adapted to be actuated by a V-shaped cam recess in a cam plate I22 fastened in a recess of a vertically reciprocating cam bar I24. The cam bar is guided in a vertically elongated box or guide (Figs. 1, 3 and 12) comprising a body I26 of U-shaped cross section and a connected cover I28, the guiding unit being fastened to one side of the bracket 6. Holding pins I30 project inwardly of the guide into opening of hardened guiding plates or inserts I32 and I34. Holding pins also project inwardly from the cover I 28 to support a. hardened insert I36 which occupies 'a groove I3 8 in the cover. The hardened insert I36 has a rectangular opening for a strong leaf spring I40 interposed between the cover and the cam bar I24 to hold the latter in its elevated or depressed position. A portion of the guide body I26 is cut out at I42 and a portion of the cover is similarly cut out at I44 to letthe cam plate I22 reciprocate and engage the cam follower I 20.

The lower end of the cam bar I24 has a horizontal projection I45 which is rigidly connected to a horizontal projection I43 on the upper end of an actuating link I50, the connection comprising a key I52 engaging grooves in the two projections with a holding screw I53 passing through a slot in the extension I48 into a tapped hole in the extension I46. The cam bar I24 and the actuating link I50 are thus in effect a single member. The lower portion of the link is laterally curved or offset and its lower end has a projecting cross pin I54 engaging slots in a forked arm I 56 of a, bell crank lever which is j ournalled for rockin movement on a bushing carried by a shouldered stud I53 which is threaded in a plate "I60 fastened on the arcuate exterior of the oscillating head 90. A vertical depending arm I62 of the bell crank lever is adapted to engage alternately with abutment screws I64 and I66 each clamped by a nut in adjusted position on a lug of a stop bracket I68 fastened ina fixed position on the fixed base III] of themachine. The two abutment screws are spaced apart about 120 and the oscillating head causes the opposite sides -of the arm I52 to alternately engage the screws to actuate the rock shaft 98 and-the feeding and ejecting mechanism. Fig. 3. indicates the amplitude of oscillation by two broken line showings of the grindin wheel but it will be understood that the grinding wheel remains in its own plane and that all other parts oscillate except the base and the abutment screws with their supporting brackets;

The cam and cam bar are shown in an intermediate'and transitory position in Fig. 2 with the point of the cam follower I2|lpulled into the V- shaped recess of the cam plate I22. In this position, the ejecting fingers H8 have been projected over the work rest to eject a finished roller at one side of the grinding wheel while the in-feed finger 24 has been advanced into the work guide to move a roller side'wise over the entrance to the chute 22. This is the position of the parts only at the instant of reversal of the stroke and the cam immediately continues its upward or down- -ward stroke to retract the ejecting finger-sand the in-feed'fin'ger. The last roller in the chute then drops from the fingersII8 onto the work 5 positions.

In practice, the chute contains a plurality or column of rollers each supporting the next one above it so that the roller next above the one being ground has only a short distance to fall in. order to replace a finished roller. Several rollers are manually fed into the chute initially to form the column which is then maintained because of the infeed of a new roller whenever a finished I one is ejected. As a finished roller is ejected, the

column of rollers is momentarily supported on the ejecting fingers which are immediately retracted. The space between the slit extension as and the Work rest is slightl greater than the diameter of a work piece and all work pieces above the one in grinding position are held from contact with the grinding wheel although several rollers will be engaged by the regulating wheel. Every new piece reaching the work rest is immediately rotated due to the rotation of the regulating wheel and the impulse to rotation imparted by withdrawal of the ejecting. fingers.- In Fig. 6, the clearance between the ends of the roller and the parallel vertical edges of the guiding plates :2 is exaggerated but should be no .more than .001 of an inch for satisfactory generation of barrel rollers for roller bearings. The

distance between those parallel edges is established by the parallel'edges 83 of the work rest.

I claim: I v 1. Ina centerless grinding machine having a grinding wheel and an oscillating unit support- 6 ing a regulating wheel and awor'kres t, a work feeding mechanism mounted on the oscillating unit to oscillate therewith, said mechanism comprising work guiding means for maintaining a plurality of work pieces substantially aligned with the work rest during said oscillation, and means actuated by oscillation of said unit for removing a ground work piece from the work rest and inserting a new piece thereon from the aligned work guiding means when the w'ork' rest and the regulating 'wheelmove beyond the side of the grinding wheel in either direction.

Ina centerless grinding machine having a grinding wheel and an oscillating unit supporting regulating wheel and a work rest, 'a single work feeding mechanism mounted on the oscillating unit, said mechanism comprising a work chute and end guiding plates aligned with the work rest at all times, and means for causing said mechanism to place a new 'work piece on the work rest at the end of each stroke of the oscillating unit.

3. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a work rest, .a work feeding mechanism mounted above the regulating wheel, a reciprocating cam for actuating said mechanism, and means actuated by oscillation of the unit for reciprocating theca-m. I

4-. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a work rest, the wheels being similarly curved crosswise 'to generate a curvature on interposed work pieces, the unit being mounted to oscillate aroundanaxist'o carry the work rest beyond the side of the grind-. ing wheel at each stroke, .and'means mounted on the oscillating unit and actu-atedat the end of each stroke for removing a groundwork piece from thework rest and supplying a new piece thereto, said means comprising work guides per-l manently in line with the work rest for holding a plurality of work pieces inperipheral contact,

andan ejecting finger oscillatediacross the work 5. In a centerless grinding machine, having a grinding wheel and an-oscillating unit supporting a regulating wheel and a work rest, theunit being mounted for-oscillation to-carrythe work rest beyond the side of the grinding wheel at each stroke, the regulatingwheel having a width less grinding wheel and an oscillating unit supporting a regulatingwheel and a work rest, the unit being mounted for oscillation to carry the work rest beyond the side of' the. grinding wheel at each stroke, the regulating wheel having 'a width less than the length of the workpieces, work engaging fingers alongside of the regulating wheel and spaced apart a distance less than the length of thework pieces, a workchute mounted on'the' oscillating unit and terminating adjacent to the rest, and means for projecting the fingersbeing wheel having a width less than the length of the work pieces, work engaging fingers embracing the regulating wheel and spaced apart a distance less than the length of the Work pieces, and means for moving said fingers over the work rest to remove a work piece therefrom when the oscillating unit carries the rest beyond the grinding wheel in either direction.

8. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a work rest, a work chute mounted upon the oscillating unit and extending downwardly close to the work rest, the regulating wheel having a width less than the length of the work pieces, and an arm having fingers embracing the regulating wheel and spaced apart a distance less than the length of the work pieces to remove a finished work piece from the rest and lower a new piece from the chute when the oscillating unit moves the rest beyond the side of the grinding wheel in either direction.

9. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a, regulating wheel and a work rest, the unit being mounted for oscillation to carry the work rest beyond the side of the grinding wheel at each stroke, a work chute mounted on the oscillating unit in the plane of the regulating wheel and terminating above the blade, a work ejecting and feeding member movable between the chute and the rest, and means actuated by the oscillating unit at the end of each stroke for reciprocating said member.

10. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a work rest, the unit being mounted for oscillation to carry the work rest beyond the side of the grinding wheel at each stroke, a work chute mounted on the oscillating unit and having side walls adjacent to the wheels, the Wall adjacent to the grinding wheel being the longer and coacting with the regulating wheel to guide the work pieces, such longer wall terminat- Y ing above the work rest at a distance therefrom to wheel, a regulating wheel, and a work rest, a work chute in the plane of the regulating wheel, the chute having side-walls and end walls, the side wall adjacent to the'grinding wheel extending downwardly beyond the opposite side wall to coact with the regulating wheel in guiding the work pieces to the work rest, said side wall terminating above the'work rest at a distance to form an exit passage for a finished work piece therebetween, and mechanism for expelling a finished work piece through 'said passage at one side of the grinding wheel.

12. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a' work rest, the top of the work rest having a length slightly exceeding the length of the work pieces, work locating plates engaging the endsof the work rest and projecting above it for a distance greater than the diameter of a work piece in order to hold a plurality of contacting work pieces substantially aligned with the work rest, the lower portions of said plates having parallel surfaces to engage the ends of the lowest work piece and limit its endwise movement along the rest when the oscillating unit traverses the work piece along the grinding wheel in either direction.

13. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a work rest, the top of the work rest having a length slightly exceeding the length of the work pieces, work locating plates engaging the ends of the work rest and projecting above it, said plates having parallel surfaces to engage the ends of the work pieces and limit their endwise movement along the rest when the oscillating unit traverses the Work pieces along the grinding wheel, and downwardly converging guide surfaces on said plates to guide the work pieces between the parallel surfaces.

14. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a work rest, the top of the work rest having a length slightly exceeding the length of the work pieces, work locating plates engaging the ends of the work rest and projecting above it, said plates having parallel surfaces to engage the ends of thework pieces and limit their endwise movement along the rest when the oscillating unit traverses the work pieces along the grinding wheel, and a work chute extending downwardly between the wheels to conduct work pieces between said parallel surfaces.

15. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a, regulating wheel and a work rest, a work chute mounted on the oscillating unit and extending downwardly between the wheels to guide a column of work pieces to the work rest, and means for removing a work piece from the rest and supplying a new piece to the rest and another to the chute at each stroke of the oscillating unit.

16. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a work rest, a work chute mounted on the oscillating unit and extending downwardly between the wheels to guide a column of work pieces to the work rest, and means for intermittently lowering the column by the dimension of one piece.

17. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a work rest, a work chute mounted on the oscillating unit and extending downwardly between the wheels to guide a column of work pieces to the work rest, and means for intermittently lowering the column, said means comprising an eject-ing member and an infeed member, and a cam actuated by the oscillation of the unit for operating said members.

18. In 'a centerless grinding machine having a grinding wheel and an oscillating unit supporting a, regulating wheel and a work rest, a work chute mounted on the oscillating unit and extending downwardly between the wheels to guide a column of work pieces to the work rest, a finger projectable between the Work rest and the chute, and means for reciprocating the finger to remove a finished piece from the work rest and lower the column of rollers to apply a new piece to the work rest.

19. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a work rest, a work chute mounted on the oscillating unit and extending downwardly between the wheels to guide a column of work pieces to the work rest, a work engaging member, a cam shiftably mounted on the oscillating unit to reciprocate said member, means controlled by oscillation of the unit for reciprocating the cam, and a spring for frictionally holding the cam at each extremity of its movement.

20. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a Work rest, a work chute mounted on the oscillating unit and extending downwardly between the Wheels to guide a column of work pieces to the work rest, and means for controlling the passage of the work pieces through the chute, said means comprising a cam mounted to reciprocate'on the oscillating unit, a spring for frictionally holding the cam at each end of its stroke, a pair of fixed abutments, a movable lever carried by said unit in a position to engage the abutments in alternation, and a connection between the lever and the cam.

21. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a Work rest, a bracket mounted on the oscillating unit and extending above the regulating Wheel, a work chute mounted on the bracket and extending downwardly towards the work rest, a rock shaft journalled in the bracket, a work engaging arm fixed to the rock shaft, a bar guided by the bracket, a cam and a cam follower, one fixed to the bar and one fixed to the rock shaft, and means for reciprocating the bar as said unit oscillates.

22. In a centerless grinding machine having a grinding wheel and an oscillating unit supporting a regulating wheel and a work rest, a work chute 10 mounted above the regulating wheel and extending downwardly towards the work rest, and means for intermittently supplying work pieces to the chute, said means comprising a rock shaft, a yoke fixed to the rock shaft and embracing the chute, an in-feed finger attached to the yoke, and a cam reciprocated by the oscillation of said unit for rocking the shaft.

23. In a centerless grinding machine having a grinding wheel and an oscillating unit, a regulating wheel, a Work rest, a pair of Work locating plates and a work chute all mounted on said unit to oscillate therewith, the work chute being maintained in the plane of the regulating wheel and leading to the work rest, the work locating plates being spaced apart at the ends of the work rest, and means for ejecting a ground roller from the rest and substituting a new roller from the chute at the end of every stroke of oscillation.

RAYMOND H. CRAM'ER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,611,135 Sanford Dec. 14, 1926 1,654,236 Binns Dec. 27, 1927 2,156,562 Cramer May 2, 1939 

